No. Superman flies in space for fun when he first discovers he can fly. Superman flies through space in order to rescue Lois from her damaged escape pod. Superman takes a round trip up to the orbiting Wayne Enterprises satellite and back. Less overt feats include walking through the burning oil rig without breathing apparatus, remaining underwater during an entire flashback sequence, traveling at extraordinary speed which would rip the air from one’s lungs, and routine feats of super-human strength as discussed in MOSAIC Episode 4. Whether or not you accept these later examples, the first three are undeniable proof that Superman does not have to be within (and breathing) Earth atmosphere to have his strength and powers.
This is both the typical Superman tradition and a logical application of our understanding of what respiration does for us. Simply put, we breathe oxygen in order to biochemically “burn” our food stores for energy. Therefore, it is logical that Superman bypasses the need for oxygen because he primarily metabolizes sunlight, rather than food, and that his feats would consume more energy than food stores could ever provide.
Why do some think he needs Earth’s atmosphere to be strong?
They are likely drawing a few faulty conclusions. First, that Jor-El’s atmosphere line pertained to Superman’s powers. Second, that Jor-El changing the atmospherics on the ship was giving Superman back the source of his strength, rather than understanding that the main point was to take away the Kryptonian atmosphere that was suppressing Superman’s strength (he adapted it to Earth merely to kill two birds with one stone and allow Lois to breathe freely if her helmet was to be compromised). Addressing each in turn:
Didn’t Jor-El say Earth’s atmosphere made Superman strong?
No. Here are the lines:
Your cells have drunken its radiation strengthening your muscles, your skin, your senses. Earth’s gravity is weaker, yet its atmosphere is more nourishing. You’ve grown stronger here than I ever could have imagined.
This is supported by Jax-Ur’s statement:
The strength you derived from exposure to the Earth’s sun has been neutralized aboard our ship.
It couldn’t be any clearer. Here, radiation is credited with increasing Superman’s strength.
Why does Jor-El mention atmosphere and gravity at all?
To explain how and why Kal-El can survive in a different environment than Krypton’s harsher environment. It isn’t to explain how or why his powers work, since both Jor-El and Jax-Ur link Superman’s strength to radiation and Superman is powered even under differing gravity and differing atmospheric conditions.
By way of analogy, imagine Krypton is Hoth and Earth is Endor. A Hoth native could live and thrive on Endor without issue. However, an Endor native wouldn’t be able to survive on Hoth without technological assistance (warm clothing; analogized to a breather).
The nourishing aspect of the atmosphere can be explained concisely in a video like this:
Thus the quality of Superman’s body is conceivably better than if he were raised on Krypton, but it doesn’t factor into what actually gives him his powers.
Didn’t changing the Black Zero’s atmospherics to Earth’s make Superman strong?
The venting of the suppressing Kryptonian atmosphere returned Superman’s powers. The breathing of Earth atmosphere did not grant Superman powers. If Superman were dependent on Earth’s atmosphere for his strength, then he would have lost it the moment he struck the panel and blew out the atmosphere. Superman would have been powerless in all of the examples we gave in our first answer.
If Jor-El could have vented all atmosphere (and, likely, he could not- Jor-El had limited control over the Black Zero, which is why klaxons begin to sound when he makes his changes and why Jor-El could not proactively stop the Kryptonians on his own), that would have also restored Superman’s strength by removing the suppressing Kryptonian atmosphere. However, that would have increased Lois’s vulnerability if her helmet was compromised during her escape.
If Superman doesn’t need to breathe, why did he get weak in the first place?
Breathing is an autonomous life function and reflex. Moreover, it is a key component of basic communication. If Superman had held his breathe and not said a word, he could have maintained his strength, but he would have no reason to do so having no foreknowledge of this Kryptonian atmospheric effect.
As to why Kryptonian atmosphere would affect Superman, we discussed the topic thoroughly in MOSAIC Episode 7, discussing Superman’s weaknesses, where we set forth an argument for a biochemical reaction (as opposed to the classic radiological Kryptonite reaction).
Why didn’t Superman carry a respirator with him to fight the World Engine?
First, they were uncertain whether the World Engine would even have an effect on him.
Second, time was of the essence.
Third, no expedient man-made respirator would have survived the trip. Superman traveled 12,450 miles in about a minute, which is about 747,000 miles per hour or roughly Mach 980. For reference, the Space Shuttle tops out at about Mach 23 for reentry into atmosphere and the fastest theoretical ballistic missile we can build today would be Mach 5. The speed would tear up anything he tried to carry.
Fourth, as we’ve already determined, if he held his breath he wouldn’t be subject to the suppressive aspects of Kryptonian atmosphere although we don’t know if he’s had the time to work out the specifics at this point.
Wait, then what was Zod breathing in Smallville?
Listen to MOSAIC Episode 6, all about this topic, explaining the weakness, the powers, equipment, and the environment.
Doesn’t David Goyer say Superman needs to breath?
Yes. This is an October 29, 2015 update to a December 2014 article. Goyer’s position is that their Superman needs to breathe, can hold his breath for a very long time, but still can’t make it all the way to the moon without breathing. I fully accept that is his position and perhaps his intentions, but I think that’s slightly less consistent with the actual film than my apologetics. If Superman does need to breath, we have to work out the explanations for why he can audibly grunt in space, why Jor-El doesn’t warn him to hold his breath before exposing himself to vacuum, how he manages to hold is breath even while unconscious, and more. While we probably could come up with explanations and rules for each of these cases, the position that he doesn’t requires fewer special-case explanations.
Since it isn’t explicitly stated in the film, I chalk this up to persuasive creator intention, but not canon since it didn’t make it into the film.
Does Batman v. Superman: Dawn of Justice shed any light on this?
Yes. This is an April 19, 2016 update to a December 2014 article. The most obvious additional point of data and support is Superman taking Doomsday into the upper atmosphere to mitigate collateral damage. This reinforces the point or possibility that Superman does not need to breathe a few different ways: 1) The speed at which they traveled makes breathing impossible (discussed above); 2) The environment in which they were in makes breathing impossible; 3) The nuclear explosion is definitely unbreathable conditions; and 4) Superman’s unconsciousness and death-like stillness imply no breathing was occurring.
Superman’s regeneration seems overtly, directly, and expressly due to the Sun and there’s little to no indication of inhalation as key.